Jack with lifting movement by wedging action and downward movement along a helicoidal guide



De- 4, 1962 J. J. RoussEAu JACK WITH LIFTING MOVEMENT BY WEDGING ACTION AND DOWNWARD MOVEMENT ALONG A HELICOIDAL GUIDE 4 Sheets-Sheet l Filed Deo. 28, 1960 Dec. 4, 1962 J. J. ROUSSEAU 3,066,914

JACK WITH LIFTING MOVEMENT BY WEDGING ACTION AND DOWNWARD MOVEMENT ALONG A HELICOIDAL GUIDE Filed Dec. 28, 1960 4 Sheets-Sheet 2 L mlm- Dec- 4, 1962 J. J. ROUSSEAU JACK WITH LIFTING MOVEMENT BY WEDGING ACTION AND DOWNWARD MOVEMENT ALONG A HELICOIDAL GUIDE 4 Sheets-Sheet 3 Filed Dec. 28, 1960 Dec. 4, 1962 J. J. RoUssEAu 3,066,914

JACK WITH LIFTING MOVEMENT BY WEDGING ACTION AND nowNwARn MOVEMENT ALONG A EELIcoInAL GUIDE Filed Dec. 28, 1960 Y 4 Sheets-Sheet 4 Fig/z DWL-:1MM 34m mlLE/EMNL Emi ilnite States Patent fifice Patented Dec. 4.-, l92

3,066,914 JACK WHTH LIFTING MOVEMENT BY WEDG- ING ACTIQN AND DOWNWARD MVE- h/IENT ALQNG A HELICIDAL GUIDE .lean Jacques Rousseau, S Rue Diderot, Issy-les-Moulineaux, France Filed Dec. 28, 196), Ser. No. 78,940

Claims priority, application France Dec. 29, 1959 12 Claims. (Cl. 25d- 105) The present invention relates to jacks having a lifting movement obtained by means of wedging plates.

In the usual types of jack with wedging lift, the upward movement is effected by means of a device comprising a lever and two members (plates or rings) adapted to jam in position on a column, one of these members being employed to lift the load and the other to maintain the load substantially at the height to which it is lifted. These two members (plates or rings) act by wedging or jamming effect, and there is obtained an effective lift which is less than the height obtained by the lifting efforts, a small amount of slip being required before the stable position of wedging becomes operative. With the load lifted, when it is desired to lower it, it is necessary to remove the wedging action and this results in an abrupt descent.

The invention overcomes these drawbacks by replacing the wedging member which holds the load at the height of lift, by a member which permits a smooth downward movement comparable with that of a hydraulic jack, and prevents the lowering movement from being caused accidentally, thus providing a greater safety in use and enabling any loss of height between two lifting movements to be avoided.

The jack according to the invention comprises essentially a column along which the upward movement is effected, a wedging member sliding along said column and adapted to be jammed on said column so as to serve as a point of support to a driving member such as a lever or a cam, a lifting member which can be rigidly fixed to the load to be lifted and adapted to receive from the said driving member supported on said wedging member, elementary upward movements along said column, and a nut engaged in a helicoidal guide such as a sloping face or a threading carried by the column, said nut being coupled to said lifting member by means enabling said nut to follow while rotating along the helicoidal guide, the upward movements of said lifting member and enablng said lifting member, when the latter is not urged upwards by said driving member, to rest on said nut in such manner as to prevent the said nut from rotating while moving downwards along the column.

The wedging member will preferably be a plate and the lifting member adapted to be made xed to the load to be lifted will preferably be a casing containing the plate and the nut. The driving member will generally take the form of a lever.

When the casing is lifted by means of the lever, the latter being supported on the plate which is wedged on the column, the coupling between this casing and the nut will cause the latter to rotate while moving upwards along the column. When the effort applied to the lever is removed, the casing rests on the nut. In order to cause the casing to move downwards, the nut is rotated.

In order that this device may operate satisfactorily, it it necessary that the nut-guide couple should be reversible, so that the effort applied on the nut during the course of the upward movement by the coupling which joins it to the casing may cause the said nut to move upwards with the casing. On the other hand, it is necessary that the device which comprises the casing resting on the nut coupled to the column should be non-reversible, in order that the weight of the casing and of the load which it supports is not liable to cause rotation of the nut and the consequent downward movement ofthe jack.

In accordance with one form of embodiment of the invention, the jack comprises a column provided with a helicoidal guide, a nut having the same thread pitch as the said helicoidal guide and engaged on said column, a wedging or jamming plate also engaged on said column, a casing containing the nut and the plate and adapted to be made fixed to the load to be lifted, a rotating member such as a ball thrust-bearing xed to the nut, a coupling between this rotating member and the casing, an elastic coupling between said casing and the plate and a cranked lever having one of its extremities pivotal`y mounted on said casing and having its elbowed portion supported on the plate, the support of said casing on said nut being effected in the position of rest by a truncated cone with the interposition of a lining having a large coeicient of friction, the said nut being further provided with a member enabling it to be given in rotation.

The coupling between the casing and the rotating member fixed to the nut may be elastic; it may also be effected by means of an abutment member in order that, when the cranked lever is supported on the plate wedged on the column so as to move the casing upwards, the said abutment member carries upwards the whole of the said roating member and the nut, the conical surface of which, provided with a friction lining, is then separated from the conical portion of the casing by a small distance. When the effort applied on the lever is released, the casing becomes seated with its conical portion on the nut; the surfaces in contact may be large without unduly increasing the overall size of the unit, so that the friction of the lining on the bearing surface of the casing is sufficient to ensure the non-reversibility of the system without there being any need to complete this non-reversibility by a ratchet device.

In accordance with a further form of embodiment of the invention, the coupling between the casing and the rotating member coupled to the nut is elastic; by this means, provided that the nut-guide couple is reversible, the effort applied by this elastic coupling during the course of an upward movement of the casing causes the nut to move upwards while rotating along the coumn until it has rejoined the said casing, which then rests on the nut. The bearing surface of the casing on the nut may be constituted by flat surfaces; between these surfaces there is inserted a ring having a very high coefficient of friction. The non-reversibility of the system is preferably completed by a ratchet device which prevents the rotation of the nut in the direction of downward movement, this ratchet device being releasable in such manner that it is possible to put the nut in rotation at will by an external means so as to cause the casing to move downwards.

The description which follows below with reference to the accompanying drawings (which are given by way of example only and not in any limitative sense) will bring out quite clearly the ditferent particular features of the invention and the manner in which they are carried into effect, any arrangement brought out either in the text or in the drawings being understood to fall within the scope of the present invention.

FG. l is an elevational sectional view of an embodiment of my new jack taken along line I-I of FIG. 2.

FIG. 2 is a side view thereof partly in section taken along line II-II of FIG. 1.

FIG. 3 is an elevational sectional view of another embodiment of my new jack, and

FIG. 4 is a sectional view along line Ill-Ill of FIG. 3.

In the embodiment shown in FIGS. l and 2, the upright of the jack is formed by a round tube or rod l which is provided with a reversible helicoidal guide groove 2,

aoeaoie and which rests in a base s. A nut 4 engages the heli coidal guide groove 2 for displacement along the upright 1. A grip clutch 5, provided with an orifice 6 bored toy a diameter very slightly greater than that of the upright 1 is movable along said upright. A casing 7 adapted to support the load to be lifted encloses the nut 4 and the late 5, and is displaced along the upright 1 which freely passes through the orices 8 and 9.

The nut 4 rests with its lower end face on a ball thrustbearing 10 comprising a dished member or lower race 10a and a cap or upper race 10b between which are housed balls ltlc. The cap 10b is engaged in the lower part of the nut 4, and the lower race 16a rests on a washer 11 which in turn rests on an abutment 12 provided on the casing 7. The upper part of the nut 4, is of frusto-conical shape and carries a lining 13 having a high coei'lcient of friction, on which is supported a frusto conical bearing face 1d of the casing 7. The nut 4 with bearing lil with washer 11 mounted between said abutment 12 and `bearing face 14 with suiicient play in order that, when the casing 7 is urged upwards tending to lift the nut through the intermediary of the abutment 12, washer 11 and bearing 10, there is left a small interstice between the bearing face 14 and the lining 13. On the other hand, when the casing 7 is urged downwards, the bearing face 14 rests on the lining 13, and the play is taken up in the bearing 1t) between the base of the nut 4 and the washer 11. The outer edge of the lower race 11M is made sufficiently high for the balls 11B to prevent their escape.

The nut 4 is additionally provided with straight teeth 15 parallel to the axis of the upright 1, these teeth engaging a bevel pinion 16 rotatably mounted in the casing 7 and extended to form a head 17 cut to a hexagon so that it Vcan be operated by -a wheel-brace or the like.

A spring 18 interposed between the bottom of the casing 7 and the clutch plate 5 urges the latter upwards. The ca3ing'7 is provided with a window 19 through which passes the laterally projecting nose 5a of the plate 5. A cranked lever 2i? terminates in a fork 20a, the two arms of which are pivotally mounted on a common shaft 21 fixed at l21a and 21h to the casing 7 by any known means, for example by riveting. The elbowed portion of the fork Zilla passes into the window 1&9 and carries a roller 2,2 which cooperates with the nose 5a of the plate 5 and is rotatably mounted on the pivot 22a between the two arms of the said fork. The outer end of the lever 2i) may be cut for example in the shape of a hexagon h for engagement with a tube or the wheel-brace for the actuation of the jack.

`The coupling of the jack to the vehicle or other object to be lifted is effected by known means. For example two sideplates 23a and 23h of a forked member 23 are pivotally mounted at 24a and .24b on the casing 7. A square tube 25 rotates about ra shaft Z6 xed to the forked member 23. When the jack is in working position as shown in FIG. l, the tube 25 is fitted into a guide 25a xed to the vehicle to be lifted and comes into abutment for rotation against the part 23cof the forked member 2 3. 'Ihe penetration of the tube 25 into the guide 25a is limited by the stop 2511 fixed to the said tube 25. In the position of rest, the forked member is folded back at 23 and the square tube at 25 as shown in dotted lines in FIG. 1.

As appearing from FIG. 2 the casing 7 is composed of two parts connected by a joint 7a along its plane of symmetry, which is the plane of FIG. l. This arrangement permits to assemble all elements of the device within the casing.

In order to cause the jack to lift, pressure is applied to the lever 2@ in the direction of the arrow 27. The roller 2x2 presses on the nose 5a of the clutch plate 5' and jams the latter on the upright 1. Thev lever4 2d turns in' clockwise direction around the roller 22 pressed against the plate 5, and by means of the shaft 21 lifts the casing 7 and the Vehicle coupled thereto as described above. During this upward movement the abutment 12 of the casing 7 urges the nut 4 upwards as has been previously explained, the play being consumed in such manner that the lining 13 no longer contacts the bearing face 14. Said upward lift is transmitted to the nut 4 by the ball thrust-bearing 19 which does not obstruct the rotational movement of the nut 4, so that the latter moves upwards with the casing 7 while rotating along the upright 1, and rotates the pinion 16 by means of its teeth 15.

When force is no longer applied on the lever 2t) in the direction of the arrow 27, the weight of the vehicle tends to cause the casing 7 to move downwards, the casing coming to rest under pressure with its bearing face 14 on the lining 13 of the nut 4. if the contact friction between this lining 13 and the bearing face 14 is sufficient the nut 4 is prevented from rotation and the casing 7 and the lifted vehicle or other object rests on the nut 4 which remains stationary on the upright 1. If the free end 2Gb of the lever 2? is then lifted in the direction opposite to that of the arrow 27, the lever 2@ pivots about theshaft 21 and the roller 22 is raised and disengages from the nose 5a of the plate 5. The latter is thereby loosened on the upright 1 and is moved upwards by the spring 1S sitting on the `bottom of the casing 7 until the position shown in FiG. l, is reached, the jack being then ready for a new upward movement effected by existingV pressure on lever 2t) in the direction of arrow 27 as described above.

The jack is thus lifted by a succession'of downward and upward movements of the lever 26, the loss of height after each upward movement or" the casing 7 being limited to that necessary for taking up the play so as to permit the lining 13 to be freed from the bearing face 14. For lowering the jack, it is only necessary to engage a wheel brace or similar tool with the hexagon 17 and to rotate in the appropriate direction (left-hand in the case shown in the drawing). The conical pinion 16 engaging the teeth 1S, rotates and thereby lowers the nut 4 along the guide groove 2. The resistance to be overcome in this movement is that which is due to the friction of the lining 13 on the bearing face 14. As soon as the actuation of the hexagon .17 has ceased, the nut 4 ceases to rotate and the casing 7 again comes to rest on the nut 4 which remains stationary on the upright 1. The downward movement is thus under perfect control and the jack can be left at any moment at the desired height durinU the course of the downward movement.

7lhe operation of the jack is conditioned by the pitch of the helicoidal guide groove 2 as a function of the coeiiicient of friction of the lining 13 on the bearing face 14 and by the apex angle of the cone which constitutes the said bearing face. The pitch of the guide groove 2 should be held between two limits: a lower limit, below which the movement of the nut along the guide groove would be absolutely irreversible (the nut 4 would notV follow the upward movements of the casing 7), and an upper limit above which the system would be reversible for downward movement (the casing 7 supporting the weight of' the vehicle or the like and resting on the nut 4 would cause the latter to rotate in the downward direction). These two conditions of reversibility for upward movement and irreversibility for downward movement also impose an upper limit and a lower limit on the apex angle of the cone which constitutes the bearing face 14, it being possible to vary these limits to a certain extent as a function of the pitch of the helicoidal guide groove 2.

lt should be further observed that in determiningthe limit of irreversibility for downward movement, account must be taken of the coecient of friction during motion of Ithe lining 13 on the bearing face 14 and not only on the coeflicient of friction in the position of rest. ln fact, if account were taken only of the latter coefficient, which is greater than the former, there would be a risk of producing a system which would be irreversible at rest and sneden;

reversible in motion, and the equilibrium of the jack would then be unstable. When once the rotation of the nut 4 was started in the lowering direction, the downward movement would continue under the action of gravity, without acting on the pinion l5.

The embodiment shown in FIGS. 3 and 4, again comprises an upright l constituted by a rod or a tube, the helicoidal guide groove 2 thereupon the base 3 intended to rest on the ground, the nut 4, the ball thrust bearing l@ and the plate 5 with its orifice 5. However, in this second embodiment the ball thrust bearing is elastically coupled to the casing '7 by the spring 28 which rests on the spacing members 29 and 30. In addition, when the casing 7 is not urged upwards, it rests on the ring or washer 31 interposed between the nut 4 and the casing '7. The flat faces 31a and 3l!) of the ring 3l should have a high coetiicient of friction. Finally a tooth ring shaped groove 32 cut in the base of the nut 4 cooperates with a pawl 37 in ratchetlike manner. A forked lever 33, pivoted at 34 on the casing 7, has its left-hand extremity urged downwards by a spring 35 fixed at 36 to the casing 7. This left-hand extremity of the lever 33 carries said pawl 37 which, when engaging the toothed ring 32, permits a spiraling movement of the nut 4 in upward direction, but prevents such spiraling movement in downward direction. At its right-hand extremity, the forked lever 33 carries a bearing 38 in which pivots a shaft 39 carrying at one end a toothed wheel 40 and at the other end, outside the casing 7, a hexagon 41. The hexagon is intended for engagement with the wheel brace of the vehicle for which the jack is intended or with any other suitable tool. if such tool is applied to effect a downward force shown diagrammatically by the arrow 42, the toothed wheel 40 enters into engagement with the ring 32, while the pawl 37 is disengaged from this ring, as shown in FIG. 3. The wheel brace or other tool can then be rotated in the right-hand direction so as to rotatably drive the nut 4 in the direction for downward movement by means of the said toothed wheel 40 engaging the toothed groove 32. If the force 42 ceases to act, the spring 35 returns the left-hand part of the lever 33 downwards, thereby disengaging the toothed wheel 40 from the toothed groove 32 and engaging the pawl 37 with said groove 32 to prevent the nut 4 from spiraling in downward direction.

The jack is operated for lifting by the lever 43 which is pivoted at 44 on the casing 7. This lever extends outwardly from the casing through the window 19, and its end facing the clutch plate 5 comprises an upper nose 43a and a lower nose 43h. If the lever 43 is actuated in the direction shown by the arrow 45, the upper nose 43a is pressed against the plate 5 which becomes wedged on the upright 1 and the casing 7 is lifted by means of pivot 44. The spacing members 29 and 30 which are fixed to the casing, compress the spring 28; the latter pushes upwards the ball thrust-bearing It), which causes the nut 4, to turn in the guide groove 2 in an upward helicoidal movement, until this movement of the nut 4 is stopped by the ring 31 interposed between the nut and the top wall of the casing 7. It will be observed that during this movement the left-hand part of this lever has been held in the downward position by the spring 35. It is inconsequential whether the ratchet 37 has or has not remained engaged in the groove 32, since in any case this ratchet 37 is arranged so as to permit a spiraling movement of the nut 4 in upward direction. On the other hand, when the nut 4 has rejoined the casing 7, the ratchet 37 is engaged in the groove 32 by the spring 35 and the nut 4 can no longer rotate in the direction for downward movement. The force 45 applied to the lever 43 can then be released, since the weight of the load lifted by the back forces the casing 7 against the ring 31, which stops the rotation of the nut 4 by the arising friction. If this friction is suicient to render the system non-reversible, the ratchet 37 does not need to withstand any effort in preventing the rotation of the nut 4, and only plays the part of a safety device.

When the force 45 on the lever 43 is released, as has just been stated, the nose 43a ceases to press against the plate 5 which thus becomes free and is forced upwards by the spring 13 to come into abutment against the spacing members 3d and 46 fixedly mounted in the casing 7, and is then in a good position for another operation of the lever 43. During this movement, the plate 5 remains engaged between the noses 43a and 43h and turns the lever 43 in the direction of the arrow 47. This movement of the lever 43 is followed and aided by the hand of the operator who is actuating the jack.

The lifting action of the jack is thus effected by movements alternately impressed on the lever 43 upwards and downwards. As has already been said, the downward movement is effected by means of a wheel brace or other tool engaging the hexagon 4i, applying concurrently to said tool a downward action in the direction of the arrow 42 and a rotational movement in the right-hand direction.

The coupling of the casing 7 with the vehicle or other load to be lifted is effected by a system similar to that shown in FIGS. l and 2. A square tube 48, passing through a window 49 in the casing 7, and pivoted at 50 on this casing can be engaged in a guide fixed to the vehicle to be lifted, and said tube in its raised end position abutting a stop 51 carried by the casing 7. In the position of rest, the square tube 48 pivots about the pivotal point 5ft and is folded back at 48' against the casing 7 as shown in dotted lines.

In the embodiment just described, the ratchet device 37 serves solely as a safety device, the non-reversibility of the system being obtained by the high coefficient of friction of the ring 3i. In a further embodiment, this coeiiicient of friction is slightly less great, -so that, when the ratchet 37 is freed from the ring 32 by rotation of the lever 33 in the direction of the arrow 42, the nonreversibility of the system is no longer ensured. The value of this coefcient of friction can be chosen in such manner that the jack then begins to move downwards smoothly and without jerks under the sole action of the weight of the load which it carries. The toothed wheel 40 is no longer necessary and can be dispensed with. If the ratchet 37 is engaged in the ring 32, the effort in the direction of the arrow 42 being released, this ratchet ensures the irreversibility of the system but has to withstand only a very small effort in so doing, since the rotation of the nut 4 is braked by the friction of the ring 31.

It will of course be understood that the embodiments described are only examples and that it is possible to modify them, especially by the substitution of equivalent technical means, without thereby departing from the scope of the invention. In particular, the casing may be replaced by any other moving member intended to lift the load, and its upward movement can be effected in a non-continuous manner by means of a device such as a lever supported on a wedging plate. The helicoidal groove 2 may be replaced by a thread. The ball thrust bearing lil may be replaced by a rotating stop of any other type; the coupling between this thrust bearing and the moving member such as a casing may be elastic. The lever which lifts this moving member while being supported on the wedging plate may be replaced by another member, for example by a cam.

The method of lift by an oscillating wedging or jamming plate may be replaced by any other wedging system. The bevel pinion 16 may be replaced by straight toothed gears, the incline doperation being obtained, for example, by means of a cardan shaft.

What I claim is:

1. In a jack of the friction grip type the improvement comprising in combination (rz) an upright formed by a rod or tube,

(b) non-locking helicoidal guide means on said upright formed by at least one helical component,

(c) a load supporting member slidably guided on said upright,

(d) a nut member engaging said guide means for reversible cooperation and embraced by said local supporting member with play in axial direction permitting the load supporting member to alternately rest'on and disengage from the nut member,

(e) frietional contacting surfaces between the load supporting member'and the nut member preventing the latter from downwardly spiraling along the guide means Awhen the load supporting member rests On the nut member,

(f) grip clutch means slidably embracing said upright and pivotally mounted on said load supporting member,

(g) means actuating said grip clutch means to cause the same to grip the upright and to gradually lift the load supporting member along the upright,

(h) thrust means arranged beneath the nut member and actuated by the load supporting member to upwardly spiral the nut member on the guide means while the load supporting member is lifted by said grip clutch means,

(i) and driving means mounted in the load supporting member to rotate the nut member and causing the same to downwardly spiral on the guiide means thereby lowering the load supporting member resting upon the nut member.

2. In a jack of the friction grip type the improvement comprising in combination (a) an upright formed by a rod or tube,

('b) non-locking helicoidal guide means on said upright formed by at least one helical component,

(c) a load supporting member slidably guidedon said upright,

(d) a nut member engaging said guide means for' reversible cooperation and embraced by said load supporting member with play in 'axial direction permitting the load supporting member to alternately rest on and disengage from the nut member,

(e) jamming means between the load supporting member and the nut member preventing the latter from downwardly spiraling along the guide means when the load supporting member rests on the nut member,

(f) grip clutch means slidably embracing said upright and pivotally mounted on said load supporting member,

(g) means actuating said grip clutch means to cause the same to grip the upright and to gradually lift the load supporting member along the upright,

(h) thrust means arranged beneath the nut member yand actuated by the load supporting member to upwardly spiral the nut member on the guide means while the load supporting member is lifted by said grip clutch means,

(i) and driving means mounted in the load supporting member to rotate the nut member and causing the same to downwardly spiral on the guide means thereby lowering the load supporting member resting upon the nut member.

3. A jack according to claim 1 wherein said grip clutch means comprise at least one gripping plate having an opening through which said upright is adapted to slidingly pas/s, said opening forming biting jaws grippingly to engage said upright.

4. A jack according to claim l comprising first shoulder means on the load supporting member to alternatively contact and rest upon said nut member and friction increasing means between the contacting surfaces of said shoulder means and said nut member.

5. A jack according to claim 1 comprising first shoulder means on the load supporting member to alternately rest upon said nut member, the contacting surfaces of said members being conically shaped to provide a clamp coupling.

6. A jack according to claim 1 in which the said driving means to rotate the nut member comprise a pinion rotatably mounted in the load supporting member, actuating means for said pinion and a gearing circumferentially arranged on the nut member for engagement by said pinion.

7. A jack according to claim l comprising a load receiving member pivotally mounted on said load supporting member, the outer end of said load receiving member adapted to engage the load to be lifted.

8. A jack according to claim l wherein said thrust means comprise second shoulder means arranged on the load supporting member beneath the nut member and an antifriction bearing interposed therebetween.

9. A jack according to claim 1 comprising jamming means arranged between the load supporting member and the nut member.

l0. in a jack of the friction grip type the improvement comprising in combination (a) an upright formed by a rod or tube,

(b) non-locking helicoidal guide means on said upright formed by at least one helical component,

(c) a load supporting housing slidably guided on said upright,

(d) a nut member within said housing engaging said guide means for reversible cooperation,

(e) first shoulder means on said housing located above the nut member to alternately contact and rest upon the latter,

(f) second shoulder means-on said housing located beneath the nut member said first and second shoulder means embracing the nut member with play to permit the same a limited displacement in axial direction,

(g) frictional surfaces between the first shoulder means and the nut member preventing the latter from downwardly spiraling along the guide means when the first shoulder means rests on the nut member,

(lz) grip clutch means slidably embracing said upright and pivotally mounted on said housing,

(i) actuating means for said clutch means to cause the same to grip the upright and to gradually lift the housing along the upright,

(j) an anti-friction bearing interposed between said second shoulder means and the base of the nut member permitting the same to spiral upwardly on the guide means while the housing is lifted by said grip clutch means,

(k) a rim gear circumferentially arranged on the nut member, and

(I) driving means rotatably mounted in the housing and engaging said rim gear.'

ll. in a jack of the friction grip type the improvement comprising in combination (a) an upright formed by a rod or tube;

y( b) non-locking helicoidal guide means on said upright formed by at least one helical component,

(c) la load supporting member or housing guided on said upright,

(d) a nut member within said load supporting member engaging said guide means and located to permit the housing to alternately rest thereupon and disengage therefrom,

(e) frictional contacting surfaces between the housing and the nut member preventing the latter from downwardly spiraling when the load supporting member restsv on the nut member;

(f) grip clutch means Within the load supporting member slidably embracing said upright;

(g) first thrust means integral with the load supporting member and arranged above said grip clutch means for cooperation therewith;

(h) actuating means for the grip clutch meansswingably mounted in the load supporting member and causing the grip clutch means to alternately grip the slidably 9 10 upright and to gradually lift the housing along the (n) a pinion rotatably mounted on the other lever arm upright; and adapted to engage said toothed rimg;

(i) second antifrictional thrust means arranged beneath (o) actuating means for tilting said two-arm lever to the nut member and elastically supported by the load alternately engage and disengage said pawl and said supporting member; 5 pinion from said toothed rim;

(j) a toothed rim on the nut member surrounding the l2. A jack according to claim 11, comprising a load re- Same; ceiving member pivotally attached to the load support- (k) a two-arm lever rotatably mounted 0n said housing ing member, its outer end adapted to engage the load to above said toothed rim; be lifted.

(l) a pawl supported by one arm of said lever and co- 10 `operating with said toothed rim; References Cited in the le of this patent (m) an .elastic means attached to said arm holding the UNITED STATES PATENTS pawl 1n engagement With said toothed rim to prevent the nut member, when the same is loaded by said 351,313 Peason API" 23 1907 housing, from rotating downwardly on the upright; 1D 2,227,397 Tucker Dec 31: 1940 

